basic salt

(noun)

the product of the neutralization of a strong base and a weak acid; its anion is the conjugate base of the weak acid

Related Terms

  • hydroxide
  • hydrolysis

Examples of basic salt in the following topics:

  • Salts that Produce Basic Solutions

    • When dissolved in water, a basic salt yields a solution with pH greater than 7.0.
    • There are several varieties of salts, and in this section we will consider basic salts.
    • What makes a basic salt basic?
    • An example of a basic salt is sodium bicarbonate, NaHCO3.
    • Because it is capable of deprotonating water and yielding a basic solution, sodium bicarbonate is a basic salt.
  • Overview of the Acid-Base Properties of Salt

    • As we have discussed, salts can form acidic or basic solutions if their cations and/or anions are hydrolyzable (able to react in water).
    • Basic salts form from the neutralization of a strong base and a weak acid; for instance, the reaction of sodium hydroxide (a strong base) with acetic acid (a weak acid) will yield water and sodium acetate.
    • Sodium acetate is a basic salt; the acetate ion is capable of deprotonating water, thereby raising the solution's pH.
    • Acid salts are the converse of basic salts; they are formed in the neutralization reaction between a strong acid and a weak base.
    • This video examines the hydrolysis of an acid salt, a basic salt, and a salt in which both ions hydrolyze.
  • Salts that Produce Acidic Solutions

    • Salts with acidic protons in the cation are most commonly ammonium salts, or organic compounds that contain a protonated amine group.
    • Acid salts can also contain an acidic proton in the anion.
    • From the previous concept, we know that salts containing the bicarbonate ion (HCO3-) are basic, whereas salts containing bisulfate ion (HSO4-) are acidic.
    • We determine whether the hydrolyzable ion is acidic or basic by comparing the Ka and Kb values for the ion; if Ka > Kb, the ion will be acidic, whereas if Kb > Ka, the ion will be basic.
    • Anilinium chloride is an example of an acid salt.
  • Synthesis of Amino Acids

    • A common method of resolving racemates is by diastereomeric salt formation with a pure chiral acid or base.
    • In the initial display, the carboxylic acid function contributes to diastereomeric salt formation.
    • The racemic amino acid is first converted to a benzamide derivative to remove the basic character of the amino group.
    • Next, an ammonium salt is formed by combining the carboxylic acid with an optically pure amine, such as brucine (a relative of strychnine).
    • Since amino acids are amphoteric, resolution could also be achieved by using the basic character of the amine function.
  • Basic and Amphoteric Hydroxides

    • Now we will examine amphoteric hydroxides—that is, hydroxide salts that can act as either an acid or a base, depending on reaction conditions.
    • This is a classic acid-base neutralization reaction: the HCl completely protonates all three hydroxides per mole of Al(OH)3, yielding pure water and the salt AlCl3.
    • From what we know about the basic properties of hydroxides so far, this is exactly as we would expect—so how can a hydroxide act as an acid?
    • We will now consider aluminum hydroxide's reaction in a strongly basic solution:
    • In a basic solution, it forms a bond with an OH- ion, pulling it out of solution and lowering the solution's pH.
  • Substitution and Elimination Reactions of Amines

    • Elimination reactions of 4º-ammonium salts are termed Hofmann eliminations.
    • Since the counter anion in most 4º-ammonium salts is halide, this is often replaced by the more basic hydroxide ion through reaction with silver hydroxide (or silver oxide).
    • The resulting hydroxide salt must then be heated (100 - 200 ºC) to effect the E2-like elimination of a 3º-amine.
    • First, it generates a 4º-ammonium halide salt in a manner different from exhaustive methylation.
    • Second, this salt is not converted to its hydroxide analog prior to elimination.
  • Carbon Oxides and Carbonates

    • The most basic oxocarbons are carbon monoxide and carbon dioxide.
    • The salt of carbonic acids are called carbonates and are characterized by the carbonate ion, CO32-.
    • In strongly basic conditions, the carbonate ion predominates, while in weakly basic conditions, the bicarbonate ion predominates.
    • Sodium carbonate is basic when dissolved in water (meaning it results in a basic solution upon dissolution), and sodium bicarbonate is weakly basic.
    • Although the carbonate salts of most metals are insoluble in water, this is not true of the bicarbonate salts.
  • Nucleophilicity of Sulfur Compounds

    • Although the basicity of ethers is roughly a hundred times greater than that of equivalent sulfides, the nucleophilicity of sulfur is much greater than that of oxygen, leading to a number of interesting and useful electrophilic substitutions of sulfur that are not normally observed for oxygen.
    • Sulfides, for example, react with alkyl halides to give ternary sulfonium salts (equation # 1) in the same manner that 3º-amines are alkylated to quaternary ammonium salts.
    • Although equivalent oxonium salts of ethers are known, they are only prepared under extreme conditions, and are exceptionally reactive.
    • Remarkably, sulfoxides (equation # 2), sulfinate salts (# 3) and sulfite anion (# 4) also alkylate on sulfur, despite the partial negative formal charge on oxygen and partial positive charge on sulfur.
  • Important Reagent Bases

    • Most base reagents are alkoxide salts, amines or amide salts.
    • Since alcohols are much stronger acids than amines, their conjugate bases are weaker than amide bases, and fill the gap in base strength between amines and amide salts.
    • Its basicity and nucleophilicity may be modified by steric hindrance, as in the case of 2,6-dimethylpyridine (pKa=6.7), or resonance stabilization, as in the case of 4-dimethylaminopyridine (pKa=9.7).
    • An interesting group of neutral, highly basic compounds of nitrogen and phosphorus have been prepared, and are referred to as superbases.
  • Extremely Halophilic Archaea

    • One example is Chromohalobacter beijerinckii, found in salted beans preserved in brine and in salted herring.
    • Tetragenococcus halophilus is found in salted anchovies and soy sauce.
    • The extremely halophilic Haloarchaea require at least a 2 M salt concentration and are usually found in saturated solutions (about 36% w/v salts).
    • Halophiles are adapted to conditions of extreme salt concentration, such as the Great Salt Lake in Utah.
    • Salt builds up along the Dead Sea.
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